This is an ADAMHA RSDA (Level 1) application. Research will concern individual differences in emotional response intensity. A good deal has already been learned about this dimension, such as its correlation with the magnitude and frequency of mood changes over time, as well as the health-related psychosomatic consequences of regular and intense emotional responses, e.g., headache proneness, muscle tension, insomnia, stomach disorders, and panic reactions. There are clear gaps, however, in our knowledge of emotional reactivity. We do not know why such individual differences exist or what processes serve to maintain these differences. The long-term objectives of this proposal are 1) to test a theroetical model of individual differences in emotional response intensity and emotion regulation, 2) to incorporate psychophysiological measures and paradigms into research and theory development in this area, and 3) to develop quantitative time series models of emotional processes. Specifically, the theory proposes that emotionally responsive individuals are actually underaroused and thus use their emotions to regulate their arousal level upward. Several studies examine predictions from this arousal regulation theory. Consultation with experts in arousal regulation and control theory is proposed, emphasizing emotion-regulation processes and the mental health implications of disregulation in these processes. Other studies examine hypothesized relations between physiological systems (e.g., cardiac reactivity) and differences in emotional intensity. Supervised training and experience with psychophysiological methods is proposed, with a developmental progression of skills. Finally, time series models will be developed to test aspects of this theory. Studies will assess mood, life events, coping processes, and physical health status each day for several months. Time series models (e.g., ARIMA) will be used to quantify relationships over time between these variables for each subjects, and differences between subjects will be examined. This unique application of the "idiographic/nomothetic" paradigm will demand consultation and supervision by experts. Such supervised training is proposed. In summary, 18 studies are proposed and 12 senior research scientists will be involved in supervised developmental experiences, with most of these experiences at other institutions.